#include "apue.h"
#include <errno.h>              /* for definition of errno */
#include <stdarg.h>             /* ISO C variable aruments */

static void     err_doit(int, int, const char *, va_list);

/*
 * Nonfatal error related to a system call.
 * Print a message and return.
 */
void
err_ret(const char *fmt, ...)
{
        va_list         ap;

        va_start(ap, fmt);
        err_doit(1, errno, fmt, ap);
        va_end(ap);
}

/*
 * Fatal error related to a system call.
 * Print a message and terminate.
 */
void
err_sys(const char *fmt, ...)
{
        va_list         ap;

        va_start(ap, fmt);
        err_doit(1, errno, fmt, ap);
        va_end(ap);
        exit(1);
}

/*
 * Fatal error unrelated to a system call.
 * Error code passed as explict parameter.
 * Print a message and terminate.
 */
void
err_exit(int error, const char *fmt, ...)
{
        va_list         ap;

        va_start(ap, fmt);
        err_doit(1, error, fmt, ap);
        va_end(ap);
        exit(1);
}

/*
 * Fatal error related to a system call.
 * Print a message, dump core, and terminate.
 */
void
err_dump(const char *fmt, ...)
{
        va_list         ap;

        va_start(ap, fmt);
        err_doit(1, errno, fmt, ap);
        va_end(ap);
        abort();                /* dump core and terminate */
        exit(1);                /* shouldn't get here */
}

/*
 * Nonfatal error unrelated to a system call.
 * Print a message and return.
 */
void
err_msg(const char *fmt, ...)
{
        va_list         ap;

        va_start(ap, fmt);
        err_doit(0, 0, fmt, ap);
        va_end(ap);
}

/*
 * Fatal error unrelated to a system call.
 * Print a message and terminate.
 */
void
err_quit(const char *fmt, ...)
{
        va_list         ap;

        va_start(ap, fmt);
        err_doit(0, 0, fmt, ap);
        va_end(ap);
        exit(1);
}

/*
 * Print a message and return to caller.
 * Caller specifies "errnoflag".
 */
static void
err_doit(int errnoflag, int error, const char *fmt, va_list ap)
{
        char    buf[MAXLINE];

        vsnprintf(buf, MAXLINE, fmt, ap);
        if (errnoflag)
                snprintf(buf+strlen(buf), MAXLINE-strlen(buf), ": %s",
                  strerror(error));
        strcat(buf, "\n");
        fflush(stdout);         /* in case stdout and stderr are the same */
        fputs(buf, stderr);
        fflush(NULL);           /* flushes all stdio output streams */
}

